Displaying publications 1 - 20 of 39 in total

  1. Bokhari A, Yusup S, Chuah LF, Klemeš JJ, Asif S, Ali B, et al.
    Bioresour. Technol., 2017 Oct;242:272-282.
    PMID: 28341378 DOI: 10.1016/j.biortech.2017.03.046
    Chemical interesterification of rubber seed oil has been investigated for four different designed orifice devices in a pilot scale hydrodynamic cavitation (HC) system. Upstream pressure within 1-3.5bar induced cavities to intensify the process. An optimal orifice plate geometry was considered as plate with 1mm dia hole having 21 holes at 3bar inlet pressure. The optimisation results of interesterification were revealed by response surface methodology; methyl acetate to oil molar ratio of 14:1, catalyst amount of 0.75wt.% and reaction time of 20min at 50°C. HC is compared to mechanical stirring (MS) at optimised values. The reaction rate constant and the frequency factor of HC were 3.4-fold shorter and 3.2-fold higher than MS. The interesterified product was characterised by following EN 14214 and ASTM D 6751 international standards.
    Matched MeSH terms: Hevea*
  2. Yeang HY
    New Phytol., 2007;175(2):283-9.
    PMID: 17587376
    How tropical trees flower synchronously near the equator in the absence of significant day length variation or other meteorological cues has long been a puzzle. The rubber tree (Hevea brasiliensis) is used as a model to investigate this phenomenon. The annual cycle of solar radiation intensity is shown to correspond closely with the flowering of the rubber tree planted near the equator and in the subtropics. Unlike in temperate regions, where incoming solar radiation (insolation) is dependent on both day length and radiation intensity, insolation at the equator is due entirely to the latter. Insolation at the upper atmosphere peaks twice a year during the spring and autumn equinoxes, but the actual solar radiation that reaches the ground is attenuated to varying extents in different localities. The rubber tree shows one or two flowering seasons a year (with major and minor seasons in the latter) in accordance with the solar radiation intensity received. High solar radiation intensity, and in particular bright sunshine (as distinct from prolonged diffuse radiation), induces synchronous anthesis and blooming in Hevea around the time of the equinoxes. The same mechanism may be operational in other tropical tree species.
    Matched MeSH terms: Hevea/physiology*; Hevea/radiation effects*
  3. Phan TN, Lan NT, Nga NT
    Med. J. Malaysia, 2004 May;59 Suppl B:214-5.
    PMID: 15468894
    Natural rubber from hevea brasiliensis trees (Thailand, RRIM 600 clone) of different age (8, 20, and 35 years) were characterized by size exclusion chromatography coupled with online viscometry according to their distribution of molar mass and branching index at a temperature of 70 degrees C using cyclohexane as solvent. Washing with an aqueous solution of sodium dodecylsulfate and subsequent saponification purified the natural rubber samples. With this procedure physical branching points caused by phospholipids, proteins and hydrophobic terminal units, mainly fatty acids, of the natural rubber (cis-1,4-polyisoprene) molecule, could be removed leading to completely soluble polymer samples. All samples investigated possess a very broad (10 to 50,000 kg/mol) and distinct bimodal molar mass distribution. With increasing age the peak area in the low molar mass region decreases favoring the peak area in the high molar mass region. By plotting the branching index as a function of the both, the molar mass and the age of the trees.
    Matched MeSH terms: Hevea*
  4. Oghenekaro AO, Miettinen O, Omorusi VI, Evueh GA, Farid MA, Gazis R, et al.
    Fungal Biol, 2014 May-Jun;118(5-6):495-506.
    PMID: 24863478 DOI: 10.1016/j.funbio.2014.04.001
    Rigidoporus microporus (Polyporales, Basidiomycota) syn. Rigidoporus lignosus is the most destructive root pathogen of rubber plantations distributed in tropical and sub-tropical regions. Our primary objective was to characterize Nigerian isolates from rubber tree and compare them with other West African, Southeast Asian and American isolates. To characterize the 20 isolates from Nigeria, we used sequence data of the nuclear ribosomal DNA ITS and LSU, β-tubulin and translation elongation factor 1-α (tef1) gene sequences. Altogether, 40 isolates of R. microporus were included in the analyses. Isolates from Africa, Asia and South/Central America formed three distinctive clades corresponding to at least three species. No phylogeographic pattern was detected among R. microporus collected from West and Central African rubber plantations suggesting continuous gene flow among these populations. Our molecular phylogenetic analysis suggests the presence of two distinctive species associated with the white rot disease. Phylogenetic analyses placed R. microporus in the Hymenochaetales in the vicinity of Oxyporus. This is the first study to characterize R. microporus isolates from Nigeria through molecular phylogenetic techniques, and also the first to compare isolates from rubber plantations in Africa and Asia.
    Matched MeSH terms: Hevea/microbiology*
  5. Naji, H.R., Sahri, M.H., Bakar, E.S., Soltani, M., Hamid, H.A.
    ASM Science Journal, 2014;8(1):36-43.
    Wood density and types of shrinkage were examined in two rubberwood latex timber clones of rubber (Hevea brasiliensis) namely RRIM 2020 and RRIM 2025, planted at densities of 500, 1000, 1500, and 2000 trees/ha, within a trial plot. The mean wood density showed a low descending trend towards high planting densities in both clones. Wood density was significantly and negatively correlated with planting density. The strength of correlation was moderate. The mean longitudinal shrinkage in both clones and tangential shrinkages in clone RRIM 2020 showed no significant difference among planting densities. The tangential (in RRIM 2025), radial and volumetric shrinkages in both clones decreased from low to high planting densities and the differences were more pronounced between densities of 500 trees/ha and 2000 trees/ha. The magnitudes of correlation between these shrinkages and planting density were low. The regression models indicated that wood density could be more ascribed by planting density followed by volumetric shrinkage. This study exhibited low variations in wood density and shrinkages among clones and the respective planting densities; however, RRIM 2025 was more stable than RRIM 2020.
    Matched MeSH terms: Hevea
  6. Kaida Khalid, W. Mohd. Daud W. Yusoff, Jumiah Hassan
    Dielectric properties of natural rubber Hevea brasiliensis latex were measured at frequencies 0.2 to 20 GHz, at temperatures of 2, 15, 25, 35, and 50oC and around 30-98% moisture content. Measurements were done using open-ended coaxial line sensor and automated network analyzer. As expected, results showed that dielectric constant increased with increasing moisture. From 0.2 to 2.6 GHz, the losses were governed by conductive losses but for frequencies greater than 2.6 GHz, these were mainly due to dipolar losses. The former is due to conducting phases in hevea latex, while the latter is mainly governed by the orientation of water molecules. The results were analyzed at 2.6, 10, and 18 GHz, respectively. These were then compared with the values predicted by the dielectric mixture equations recommended by Weiner, Bruggeman and Kraszewski. All the measured values were found to be within the Weiner’s boundaries and close to the upper limit of Weiner’s model. It is also close to the predicted values of Bruggeman’s model with a/b = 0.1. All the models including Kraszewski are suitable for predicting the dielectric properties of hevea latex for frequencies 2.6 to 18 GHz, moisture content 30 to 98% and temperatures 2 to 50oC.
    Matched MeSH terms: Hevea
  7. Nik Hashyati Nik Hashim, Zulkefly Sulaiman, Mahmud Tengku Muda Mohamed, Mohd Yusoff Abd Samad
    Hevea brasiliensis is one of the popular industrial crops in Malaysia better known as rubber tree belongs to the family Euphorbiaceace. From more than 12 species of Hevea, only Hevea brasiliensis is economically exploited because the milky latex extracted from the tree is the primary source of natural rubber. As in other crops, various plant physiological conditions and pathogenic diseases influence rubber production. Brown bast is one of the most serious threats to natural rubber production. In general, high-yielding clones of rubber tree are often considered to be more susceptible to this physiological disorder also commonly termed Tapping Panel Dryness (TPD). It is estimated that brown bast leads to approximately 15-20% decrease in yield. There is no known cure for brown bast yet. However, many plantation practices manage brown bast in rubber by giving tapping rest and changing tapping panel. Hence, this review condenses the causal of brown bast, symptoms of diseases and also control of brown bast affected Hevea tree.
    Matched MeSH terms: Hevea
  8. Nazarpour F, Abdullah DK, Abdullah N, Motedayen N, Zamiri R
    Biomed Res Int, 2013;2013:268349.
    PMID: 24167813 DOI: 10.1155/2013/268349
    Rubberwood (Hevea brasiliensis), a potential raw material for bioethanol production due to its high cellulose content, was used as a novel feedstock for enzymatic hydrolysis and bioethanol production using biological pretreatment. To improve ethanol production, rubberwood was pretreated with white rot fungus Ceriporiopsis subvermispora to increase fermentation efficiency. The effects of particle size of rubberwood (1 mm, 0.5 mm, and 0.25 mm) and pretreatment time on the biological pretreatment were first determined by chemical analysis and X-ray diffraction and their best condition obtained with 1 mm particle size and 90 days pretreatment. Further morphological study on rubberwood with 1 mm particle size pretreated by fungus was performed by FT-IR spectra analysis and SEM observation and the result indicated the ability of this fungus for pretreatment. A study on enzymatic hydrolysis resulted in an increased sugar yield of 27.67% as compared with untreated rubberwood (2.88%). The maximum ethanol concentration and yield were 17.9 g/L and 53% yield, respectively, after 120 hours. The results obtained demonstrate that rubberwood pretreated by C. subvermispora can be used as an alternative material for the enzymatic hydrolysis and bioethanol production.
    Matched MeSH terms: Hevea/microbiology*; Hevea/ultrastructure
  9. Makita Y, Ng KK, Veera Singham G, Kawashima M, Hirakawa H, Sato S, et al.
    DNA Res., 2017 Apr 01;24(2):159-167.
    PMID: 28431015 DOI: 10.1093/dnares/dsw056
    Natural rubber has unique physical properties that cannot be replaced by products from other latex-producing plants or petrochemically produced synthetic rubbers. Rubber from Hevea brasiliensis is the main commercial source for this natural rubber that has a cis-polyisoprene configuration. For sustainable production of enough rubber to meet demand elucidation of the molecular mechanisms involved in the production of latex is vital. To this end, we firstly constructed rubber full-length cDNA libraries of RRIM 600 cultivar and sequenced around 20,000 clones by the Sanger method and over 15,000 contigs by Illumina sequencer. With these data, we updated around 5,500 gene structures and newly annotated around 9,500 transcription start sites. Second, to elucidate the rubber biosynthetic pathways and their transcriptional regulation, we carried out tissue- and cultivar-specific RNA-Seq analysis. By using our recently published genome sequence, we confirmed the expression patterns of the rubber biosynthetic genes. Our data suggest that the cytoplasmic mevalonate (MVA) pathway is the main route for isoprenoid biosynthesis in latex production. In addition to the well-studied polymerization factors, we suggest that rubber elongation factor 8 (REF8) is a candidate factor in cis-polyisoprene biosynthesis. We have also identified 39 transcription factors that may be key regulators in latex production. Expression profile analysis using two additional cultivars, RRIM 901 and PB 350, via an RNA-Seq approach revealed possible expression differences between a high latex-yielding cultivar and a disease-resistant cultivar.
    Matched MeSH terms: Hevea/genetics*; Hevea/metabolism
  10. Rahman AY, Usharraj AO, Misra BB, Thottathil GP, Jayasekaran K, Feng Y, et al.
    BMC Genomics, 2013;14:75.
    PMID: 23375136 DOI: 10.1186/1471-2164-14-75
    Hevea brasiliensis, a member of the Euphorbiaceae family, is the major commercial source of natural rubber (NR). NR is a latex polymer with high elasticity, flexibility, and resilience that has played a critical role in the world economy since 1876.
    Matched MeSH terms: Hevea/genetics*; Hevea/immunology; Hevea/metabolism
  11. Habib MA, Yuen GC, Othman F, Zainudin NN, Latiff AA, Ismail MN
    Biochem. Cell Biol., 2017 04;95(2):232-242.
    PMID: 28177774 DOI: 10.1139/bcb-2016-0144
    The natural rubber latex extracted from the bark of Hevea brasiliensis plays various important roles in today's modern society. Following ultracentrifugation, the latex can be separated into 3 layers: C-serum, lutoids, and rubber particles. Previous studies have shown that a large number of proteins are present in these 3 layers. However, a complete proteome for this important plant is still unavailable. Protein sequences have been recently translated from the completed draft genome database of H. brasiliensis, leading to the creation of annotated protein databases of the following H. brasiliensis biosynthetic pathways: photosynthesis, latex allergens, rubberwood formation, latex biosynthesis, and disease resistance. This research was conducted to identify the proteins contained within the latex by way of de novo sequencing from mass spectral data obtained from the 3 layers of the latex. Peptides from these proteins were fragmented using collision-induced dissociation, higher-energy collisional dissociation, and electron-transfer dissociation activation methods. A large percentage of proteins from the biosynthetic pathways (63% to 100%) were successfully identified. In addition, a total of 1839 unique proteins were identified from the whole translated draft genome database (AnnHBM).
    Matched MeSH terms: Hevea/genetics; Hevea/immunology; Hevea/chemistry*
  12. Nashriyah Mat, Norhayati Ngah, Khairil Mahmud, Nurrul Akmar Rosni, Shamsiah Abd Rahman, Khairuddin Abdul Rahim
    Effects of cultural practice under different habitats, of well-managed monoculture plantation and growing wild under rubber trees, were studied in Aquilaria malaccensis (Karas) leaves. This study was carried out on Karas growing in these two habitats each from Lipis, Pahang and Sepang, Selangor areas in Malaysia; under the control and induced treatments. The parameters studied include wet and dry weight of 50 matured leaves, iron and zinc elemental contents in leaf, iron and zinc uptakes from soil, and leaf and soil moisture contents. Iron and zinc were analysed in Karas leaves and soil by using Instrumental Neutron Activation Analysis (INAA) technique.
    Matched MeSH terms: Hevea
  13. Brown D, Feeney M, Ahmadi M, Lonoce C, Sajari R, Di Cola A, et al.
    J. Exp. Bot., 2017 Nov 02;68(18):5045-5055.
    PMID: 29036360 DOI: 10.1093/jxb/erx331
    Natural rubber (polyisoprene) from the rubber tree Hevea brasiliensis is synthesized by specialized cells called laticifers. It is not clear how rubber particles arise, although one hypothesis is that they derive from the endoplasmic reticulum (ER) membrane. Here we cloned the genes encoding four key proteins found in association with rubber particles and studied their intracellular localization by transient expression in Nicotiana benthamiana leaves. We show that, while the cis-prenyltransferase (CPT), responsible for the synthesis of long polyisoprene chains, is a soluble, cytosolic protein, other rubber particle proteins such as rubber elongation factor (REF), small rubber particle protein (SRPP) and Hevea rubber transferase 1-REF bridging protein (HRBP) are associated with the endoplasmic reticulum (ER). We also show that SRPP can recruit CPT to the ER and that interaction of CPT with HRBP leads to both proteins relocating to the plasma membrane. We discuss these results in the context of the biogenesis of rubber particles.
    Matched MeSH terms: Hevea/cytology; Hevea/enzymology*; Hevea/genetics
  14. Lau NS, Makita Y, Kawashima M, Taylor TD, Kondo S, Othman AS, et al.
    Sci Rep, 2016 06 24;6:28594.
    PMID: 27339202 DOI: 10.1038/srep28594
    Hevea brasiliensis Muell. Arg, a member of the family Euphorbiaceae, is the sole natural resource exploited for commercial production of high-quality natural rubber. The properties of natural rubber latex are almost irreplaceable by synthetic counterparts for many industrial applications. A paucity of knowledge on the molecular mechanisms of rubber biosynthesis in high yield traits still persists. Here we report the comprehensive genome-wide analysis of the widely planted H. brasiliensis clone, RRIM 600. The genome was assembled based on ~155-fold combined coverage with Illumina and PacBio sequence data and has a total length of 1.55 Gb with 72.5% comprising repetitive DNA sequences. A total of 84,440 high-confidence protein-coding genes were predicted. Comparative genomic analysis revealed strong synteny between H. brasiliensis and other Euphorbiaceae genomes. Our data suggest that H. brasiliensis's capacity to produce high levels of latex can be attributed to the expansion of rubber biosynthesis-related genes in its genome and the high expression of these genes in latex. Using cap analysis gene expression data, we illustrate the tissue-specific transcription profiles of rubber biosynthesis-related genes, revealing alternative means of transcriptional regulation. Our study adds to the understanding of H. brasiliensis biology and provides valuable genomic resources for future agronomic-related improvement of the rubber tree.
    Matched MeSH terms: Hevea/genetics*
  15. Bokhari A, Chuah LF, Yusup S, Klemeš JJ, Kamil RNM
    Bioresour. Technol., 2016 Jan;199:414-422.
    PMID: 26298387 DOI: 10.1016/j.biortech.2015.08.013
    Pretreatment of the high free fatty acid rubber seed oil (RSO) via esterification reaction has been investigated by using a pilot scale hydrodynamic cavitation (HC) reactor. Four newly designed orifice plate geometries are studied. Cavities are induced by assisted double diaphragm pump in the range of 1-3.5 bar inlet pressure. An optimised plate with 21 holes of 1mm diameter and inlet pressure of 3 bar resulted in RSO acid value reduction from 72.36 to 2.64 mg KOH/g within 30 min of reaction time. Reaction parameters have been optimised by using response surface methodology and found as methanol to oil ratio of 6:1, catalyst concentration of 8 wt%, reaction time of 30 min and reaction temperature of 55°C. The reaction time and esterified efficiency of HC was three fold shorter and four fold higher than mechanical stirring. This makes the HC process more environmental friendly.
    Matched MeSH terms: Hevea/chemistry*
  16. Hashim R, How LS, Kumar RN, Sulaiman O
    Bioresour. Technol., 2005 Nov;96(16):1826-31.
    PMID: 16051090
    The flame retardancy of medium density fiberboard (MDF) made from mixture of rubberwood fibers and recycled old corrugated containers was studied. Aluminum trihydroxide (ATH) was used as a fire retardant additive and mixed with the fibers to manufacture experimental MDF panels using wet process. Phenol formaldehyde (PF) resin in liquid, 2% based on oven dry weight of fibers, was used along with 0%, 10%, 15% and 20% of ATH. The flame retardant test was done using the limiting oxygen index (LOI) test. The other properties investigated include internal bond strength, thickness swelling and water absorption. The results showed that ATH loading increased as the LOI of MDF increased. This demonstrated that ATH could improved the fire retardant property of MDF at sufficient loading. An increase in concentration of ATH showed an increase in the IB values of MDF made without resin. MDF panels made without resin showed a progressive increase in internal bond as the composition of recycled old corrugated containers fiber increased. Addition of resin improved internal bond strength and reduced thickness swelling, and water absorption. Thickness swelling of panel increased as the composition of recycled old corrugated containers fiber increased. Scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX) showed that there is indication of ATH and resin filling the void space in between fibers.
    Matched MeSH terms: Hevea/chemistry*
  17. Lee YK, Lay LK, Mahsufi MS, Guan TS, Elumalai S, Thong OM
    Pak J Pharm Sci, 2012 Jul;25(3):645-50.
    PMID: 22713955
    The rubber tree (Hevea brasiliensis) extracts are becoming increasingly visible in pharmaceutical and therapeutical research. The present study is aimed at examining the specific anti-proliferation property of H. brasiliensis latex B-serum sub-fractions against human breast cancer epithelial cell lines MCF-7 and MDA-MB231. The results showed that the latex whole B-serum and DBP sub-fraction exerted a specific anti-proliferation activity against cancer-origin cells MDA-MB231 but had little effect on non-cancer-origin cells. On the other hand, the anti-proliferative activity was diminished in the pre-heated B-serum fractions. With the low toxicity that the B-serum demonstrated previously in Brine Shrimp Lethality Test (BSLT), the present results suggest the potential use of the B-serum sub-fractions in cancer treatment.
    Matched MeSH terms: Hevea/chemistry*
  18. Daruliza KM, Yang KL, Lam KL, Priscilla JT, Sunderasan E, Ong MT
    Eur Rev Med Pharmacol Sci, 2011 Oct;15(10):1163-71.
    PMID: 22165677
    Hevea brasiliensis extracts could potentially be employed as a relatively low cost resource for various anti-fungal activities due to the simplicity of the extract preparation and its abundance especially in the tropical region. Latex B-serum was reported to have anti-cancer property and its specificity in anti-fungal property has not been elucidated. The present study was conducted to determine the anti-fungal activity of Hevea latex B-serum against Candida (C.) albicans (a rounded cell fungus) and Aspergillus (A.) niger (a filamentous fungus).
    Matched MeSH terms: Hevea/chemistry*
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